High folic acid levels causes
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High Folic Acid Levels and Adverse Health Effects
Vitamin B12 Deficiency and Cognitive Impairment
High folic acid intake can worsen health problems in people with low vitamin B12 levels, especially the elderly. Studies have found that high folate levels are linked to increased risk of anemia and cognitive impairment in those with B12 deficiency. This combination can also lead to higher levels of certain harmful blood markers, such as methylmalonic acid (MMA) and homocysteine (Hcy) Selhub2016Smith2008Maruvada2020.
Oxidative Stress and Kidney Damage
Research shows that high concentrations of folic acid can cause oxidative stress and cell damage in kidney cells. In the short term, this leads to cell toxicity, while long-term exposure can result in DNA damage and fibrotic changes, which are linked to chronic kidney disease Kandel2022Koseki2020.
Disruption of Cholesterol and Lipid Metabolism
Excess folic acid intake can disturb cholesterol balance in the liver by changing gene expression through DNA methylation. This can lead to increased cholesterol in the liver and changes in genes involved in cholesterol synthesis and transport. These effects may be more pronounced in people with certain genetic backgrounds, such as those with MTHFR deficiency . Additionally, in animal studies, high folic acid intake combined with a high-fat diet led to more weight gain, fat accumulation, and inflammation in fat tissue, along with impaired glucose tolerance .
Immune Function and Cancer Risk
High folic acid levels may reduce the activity of natural killer cells, which are important for immune defense. There is also concern that high folate status could interfere with the effectiveness of antifolate drugs used to treat conditions like cancer, malaria, and autoimmune diseases. Furthermore, while folate can help prevent cancer initiation, high levels may promote the growth of existing pre-cancerous or cancerous cells Selhub2016Smith2008.
Neurodevelopmental and Mental Health Concerns
There is ongoing debate about whether high folic acid intake during pregnancy increases the risk of autism spectrum disorder (ASD) in children. Some studies suggest a protective effect, while others report a possible increased risk with very high maternal folate levels. The evidence is mixed, and some researchers argue that other factors, such as birth order, may confound these findings Wiens2017Koren2019. Animal studies also show that high doses of folic acid during pregnancy can delay development and increase anxiety- and depression-like behaviors in offspring, possibly due to inflammation in the brain .
Insulin Resistance and Obesity in Offspring
High maternal folic acid levels have been linked to increased insulin resistance and a higher risk of obesity in children, suggesting that excess intake during pregnancy may have long-term metabolic effects on offspring Selhub2016Smith2008.
Unmetabolized Folic Acid and Knowledge Gaps
High intake of synthetic folic acid can lead to the presence of unmetabolized folic acid in the blood. The health effects of this are not fully understood, but there are concerns about its potential to disrupt normal metabolic pathways and contribute to disease risk. More research is needed to clarify these effects and guide public health recommendations Maruvada2020Wiens2017.
Conclusion
While folic acid is essential for health, especially in preventing neural tube defects, excessive intake can cause harm in certain populations. Risks include worsening of vitamin B12 deficiency symptoms, oxidative stress, metabolic disturbances, immune suppression, and possible negative effects on neurodevelopment and offspring health. The evidence highlights the need for caution with high-dose supplementation and further research to understand the full impact of high folic acid levels across different groups.
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